mcs/class/corlib/System.Security.Cryptography/CryptoStream.cs

   1 //
   2 // System.Security.Cryptography CryptoStream.cs
   3 //
   4 // Authors:
   5 //      Thomas Neidhart (tome@sbox.tugraz.at)
   6 //      Sebastien Pouliot (sebastien@ximian.com)
   7 //
   8 // Portions (C) 2002, 2003 Motus Technologies Inc. (http://www.motus.com)
   9 // Copyright (C) 2004-2005, 2007 Novell, Inc (http://www.novell.com)
  10 //
  11 // Permission is hereby granted, free of charge, to any person obtaining
  12 // a copy of this software and associated documentation files (the
  13 // "Software"), to deal in the Software without restriction, including
  14 // without limitation the rights to use, copy, modify, merge, publish,
  15 // distribute, sublicense, and/or sell copies of the Software, and to
  16 // permit persons to whom the Software is furnished to do so, subject to
  17 // the following conditions:
  18 //
  19 // The above copyright notice and this permission notice shall be
  20 // included in all copies or substantial portions of the Software.
  21 //
  22 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  23 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  24 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  25 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  26 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  27 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  28 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  29 //
  30
  31 using System.Globalization;
  32 using System.IO;
  33 using System.Runtime.InteropServices;
  34
  35 namespace System.Security.Cryptography {
  36
  37         [ComVisible (true)]
  38         public class CryptoStream : Stream {
  39                 private Stream _stream;
  40                 private ICryptoTransform _transform;
  41                 private CryptoStreamMode _mode;
  42                 private byte[] _currentBlock;
  43                 private bool _disposed;
  44                 private bool _flushedFinalBlock;
  45                 private int _partialCount;
  46                 private bool _endOfStream;
  47
  48                 private byte[] _waitingBlock;
  49                 private int _waitingCount;
  50
  51                 private byte[] _transformedBlock;
  52                 private int _transformedPos;
  53                 private int _transformedCount;
  54
  55                 private byte[] _workingBlock;
  56                 private int _workingCount;
  57
  58                 public CryptoStream (Stream stream, ICryptoTransform transform, CryptoStreamMode mode)
  59                 {
  60                         if (mode == CryptoStreamMode.Read) {
  61                                 if (!stream.CanRead)
  62                                         throw new ArgumentException (Locale.GetText ("Can't read on stream"));
  63                         } else if (mode == CryptoStreamMode.Write) {
  64                                 if (!stream.CanWrite)
  65                                         throw new ArgumentException (Locale.GetText ("Can't write on stream"));
  66                         } else {
  67                                 throw new ArgumentException ("mode");
  68                         }
  69                         _stream = stream;
  70                         _transform = transform;
  71                         _mode = mode;
  72                         _disposed = false;
  73                         if (transform != null) {
  74                                 if (mode == CryptoStreamMode.Read) {
  75                                         _currentBlock = new byte [transform.InputBlockSize];
  76                                         _workingBlock = new byte [transform.InputBlockSize];
  77                                 }
  78                                 else if (mode == CryptoStreamMode.Write) {
  79                                         _currentBlock = new byte [transform.OutputBlockSize];
  80                                         _workingBlock = new byte [transform.OutputBlockSize];
  81                                 }
  82                         }
  83                 }
  84
  85                 ~CryptoStream ()
  86                 {
  87                         Dispose (false);
  88                 }
  89
  90                 public override bool CanRead {
  91                         get { return (_mode == CryptoStreamMode.Read); }
  92                 }
  93
  94                 public override bool CanSeek {
  95                         get { return false; }
  96                 }
  97
  98                 public override bool CanWrite {
  99                         get { return (_mode == CryptoStreamMode.Write); }
 100                 }
 101
 102                 public override long Length {
 103                         get { throw new NotSupportedException ("Length"); }
 104                 }
 105
 106                 public override long Position {
 107                         get { throw new NotSupportedException ("Position"); }
 108                         set { throw new NotSupportedException ("Position"); }
 109                 }
 110
 111                 public void Clear ()
 112                 {
 113                         Close ();
 114                 }
 115
 116                 // LAMESPEC: A CryptoStream can be close in read mode
 117                 public override void Close ()
 118                 {
 119                         base.Close ();
 120                 }
 121
 122                 public override int Read ([In,Out] byte[] buffer, int offset, int count)
 123                 {
 124                         if (_mode != CryptoStreamMode.Read) {
 125                                 throw new NotSupportedException (
 126                                         Locale.GetText ("not in Read mode"));
 127                         }
 128                         if (offset < 0) {
 129                                 throw new ArgumentOutOfRangeException ("offset",
 130                                         Locale.GetText ("negative"));
 131                         }
 132                         if (count < 0) {
 133                                 throw new ArgumentOutOfRangeException ("count",
 134                                         Locale.GetText ("negative"));
 135                         }
 136                         // yes - buffer.Length will throw a NullReferenceException if buffer is null
 137                         // but by doing so we match MS implementation
 138                         // re-ordered to avoid integer overflow
 139                         if (offset > buffer.Length - count) {
 140                                 throw new ArgumentException ("(offset+count)",
 141                                         Locale.GetText ("buffer overflow"));
 142                         }
 143                         // for some strange reason ObjectDisposedException isn't throw
 144                         if (_workingBlock == null) {
 145                                 return 0;
 146                         }
 147
 148                         int result = 0;
 149                         if ((count == 0) || ((_transformedPos == _transformedCount) && (_endOfStream)))
 150                                 return result;
 151
 152                         if (_waitingBlock == null) {
 153                                 _transformedBlock = new byte [_transform.OutputBlockSize << 2];
 154                                 _transformedPos = 0;
 155                                 _transformedCount = 0;
 156                                 _waitingBlock = new byte [_transform.InputBlockSize];
 157                                 _waitingCount = _stream.Read (_waitingBlock, 0, _waitingBlock.Length);
 158                         }
 159
 160                         while (count > 0) {
 161                                 // transformed but not yet returned
 162                                 int length = (_transformedCount - _transformedPos);
 163
 164                                 // need more data - at least one full block must be available if we haven't reach the end of the stream
 165                                 if (length < _transform.InputBlockSize) {
 166                                         int transformed = 0;
 167
 168                                         // load a new block
 169                                         _workingCount = _stream.Read (_workingBlock, 0, _transform.InputBlockSize);
 170                                         _endOfStream = (_workingCount < _transform.InputBlockSize);
 171
 172                                         if (!_endOfStream) {
 173                                                 // transform the waiting block
 174                                                 transformed = _transform.TransformBlock (_waitingBlock, 0, _waitingBlock.Length, _transformedBlock, _transformedCount);
 175
 176                                                 // transfer temporary to waiting
 177                                                 Buffer.BlockCopy (_workingBlock, 0, _waitingBlock, 0, _workingCount);
 178                                                 _waitingCount = _workingCount;
 179                                         }
 180                                         else {
 181                                                 if (_workingCount > 0) {
 182                                                         // transform the waiting block
 183                                                         transformed = _transform.TransformBlock (_waitingBlock, 0, _waitingBlock.Length, _transformedBlock, _transformedCount);
 184
 185                                                         // transfer temporary to waiting
 186                                                         Buffer.BlockCopy (_workingBlock, 0, _waitingBlock, 0, _workingCount);
 187                                                         _waitingCount = _workingCount;
 188
 189                                                         length += transformed;
 190                                                         _transformedCount += transformed;
 191                                                 }
 192                                                 if (!_flushedFinalBlock) {
 193                                                         byte[] input = _transform.TransformFinalBlock (_waitingBlock, 0, _waitingCount);
 194                                                         transformed = input.Length;
 195                                                         Buffer.BlockCopy (input, 0, _transformedBlock, _transformedCount, input.Length);
 196                                                         // zeroize this last block
 197                                                         Array.Clear (input, 0, input.Length);
 198                                                         _flushedFinalBlock = true;
 199                                                 }
 200                                         }
 201
 202                                         length += transformed;
 203                                         _transformedCount += transformed;
 204                                 }
 205                                 // compaction
 206                                 if (_transformedPos > _transform.OutputBlockSize) {
 207                                         Buffer.BlockCopy (_transformedBlock, _transformedPos, _transformedBlock, 0, length);
 208                                         _transformedCount -= _transformedPos;
 209                                         _transformedPos = 0;
 210                                 }
 211
 212                                 length = ((count < length) ? count : length);
 213                                 if (length > 0) {
 214                                         Buffer.BlockCopy (_transformedBlock, _transformedPos, buffer, offset, length);
 215                                         _transformedPos += length;
 216
 217                                         result += length;
 218                                         offset += length;
 219                                         count -= length;
 220                                 }
 221
 222                                 // there may not be enough data in the stream for a
 223                                 // complete block
 224                                 if (((length != _transform.InputBlockSize) && (_waitingCount != _transform.InputBlockSize)) || (_endOfStream)) {
 225                                         count = 0;      // no more data can be read
 226                                 }
 227                         }
 228
 229                         return result;
 230                 }
 231
 232                 public override void Write (byte[] buffer, int offset, int count)
 233                 {
 234                         if (_mode != CryptoStreamMode.Write) {
 235                                 throw new NotSupportedException (
 236                                         Locale.GetText ("not in Write mode"));
 237                         }
 238                         if (offset < 0) {
 239                                 throw new ArgumentOutOfRangeException ("offset",
 240                                         Locale.GetText ("negative"));
 241                         }
 242                         if (count < 0) {
 243                                 throw new ArgumentOutOfRangeException ("count",
 244                                         Locale.GetText ("negative"));
 245                         }
 246                         // re-ordered to avoid integer overflow
 247                         if (offset > buffer.Length - count) {
 248                                 throw new ArgumentException ("(offset+count)",
 249                                         Locale.GetText ("buffer overflow"));
 250                         }
 251
 252                         if (_stream == null)
 253                                 throw new ArgumentNullException ("inner stream was diposed");
 254
 255                         int buffer_length = count;
 256
 257                         // partial block (in progress)
 258                         if ((_partialCount > 0) && (_partialCount != _transform.InputBlockSize)) {
 259                                 int remainder = _transform.InputBlockSize - _partialCount;
 260                                 remainder = ((count < remainder) ? count : remainder);
 261                                 Buffer.BlockCopy (buffer, offset, _workingBlock, _partialCount, remainder);
 262                                 _partialCount += remainder;
 263                                 offset += remainder;
 264                                 count -= remainder;
 265                         }
 266
 267                         int bufferPos = offset;
 268                         while (count > 0) {
 269                                 if (_partialCount == _transform.InputBlockSize) {
 270                                         // use partial block to avoid (re)allocation
 271                                         int len = _transform.TransformBlock (_workingBlock, 0, _partialCount, _currentBlock, 0);
 272                                         _stream.Write (_currentBlock, 0, len);
 273                                         // reset
 274                                         _partialCount = 0;
 275                                 }
 276
 277                                 if (_transform.CanTransformMultipleBlocks) {
 278                                         // get the biggest multiple of InputBlockSize in count (without mul or div)
 279                                         int size = (count & ~(_transform.InputBlockSize - 1));
 280                                         int rem = (count & (_transform.InputBlockSize - 1));
 281                                         // avoid reallocating memory at each call (reuse same buffer whenever possible)
 282                                         int sizeWorkingBlock = (1 + size / _transform.InputBlockSize) * _transform.OutputBlockSize;
 283                                         if (_workingBlock.Length < sizeWorkingBlock) {
 284                                                 Array.Clear (_workingBlock, 0, _workingBlock.Length);
 285                                                 _workingBlock = new byte [sizeWorkingBlock];
 286                                         }
 287
 288                                         if (size > 0) {
 289                                                 int len = _transform.TransformBlock (buffer, offset, size, _workingBlock, 0);
 290                                                 _stream.Write (_workingBlock, 0, len);
 291                                         }
 292
 293                                         if (rem > 0)
 294                                                 Buffer.BlockCopy (buffer, buffer_length - rem, _workingBlock, 0, rem);
 295                                         _partialCount = rem;
 296                                         count = 0; // the last block, if any, is in _workingBlock
 297                                 } else {
 298                                         int len = Math.Min (_transform.InputBlockSize - _partialCount, count);
 299                                         Buffer.BlockCopy (buffer, bufferPos, _workingBlock, _partialCount, len);
 300                                         bufferPos += len;
 301                                         _partialCount += len;
 302                                         count -= len;
 303                                         // here block may be full, but we wont TransformBlock it until next iteration
 304                                         // so that the last block will be called in FlushFinalBlock using TransformFinalBlock
 305                                 }
 306                         }
 307                 }
 308
 309                 public override void Flush ()
 310                 {
 311                 }
 312
 313                 public void FlushFinalBlock ()
 314                 {
 315                         if (_flushedFinalBlock)
 316                                 throw new NotSupportedException (Locale.GetText ("This method cannot be called twice."));
 317                         if (_disposed)
 318                                 throw new NotSupportedException (Locale.GetText ("CryptoStream was disposed."));
 319
 320                         _flushedFinalBlock = true;
 321                         byte[] finalBuffer = _transform.TransformFinalBlock (_workingBlock, 0, _partialCount);
 322                         if (_stream != null && _mode == CryptoStreamMode.Write) {
 323                                 _stream.Write (finalBuffer, 0, finalBuffer.Length);
 324                         }
 325                         if (_stream is CryptoStream) {
 326                                 // for cascading crypto streams
 327                                 (_stream as CryptoStream).FlushFinalBlock ();
 328                         } else {
 329                                 _stream.Flush ();
 330                         }
 331                         // zeroize
 332                         Array.Clear (finalBuffer, 0, finalBuffer.Length);
 333                 }
 334
 335                 public override long Seek (long offset, SeekOrigin origin)
 336                 {
 337                         throw new NotSupportedException ("Seek");
 338                 }
 339
 340                 // LAMESPEC: Exception NotSupportedException not documented
 341                 public override void SetLength (long value)
 342                 {
 343                         throw new NotSupportedException ("SetLength");
 344                 }
 345
 346                 protected override void Dispose (bool disposing)
 347                 {
 348                         if (!_disposed) {
 349                                 if (disposing) {
 350                                         if (!_flushedFinalBlock) {
 351                                                 FlushFinalBlock ();
 352                                         }
 353
 354                                         if (_stream != null)
 355                                                 _stream.Close ();
 356                                 }
 357                                 _disposed = true;
 358                                 // always cleared for security reason
 359                                 if (_workingBlock != null)
 360                                         Array.Clear (_workingBlock, 0, _workingBlock.Length);
 361                                 if (_currentBlock != null)
 362                                         Array.Clear (_currentBlock, 0, _currentBlock.Length);
 363                                 if (disposing) {
 364                                         _stream = null;
 365                                         _workingBlock = null;
 366                                         _currentBlock = null;
 367                                 }
 368                         }
 369                 }
 370         }
 371 }